JP5614361B2 - Method and apparatus for manufacturing hydroformed molded product - Google Patents

Description

  The present invention relates to a method and an apparatus for producing a hydroformed product by performing hydroforming on two superposed metal plates, and more specifically, welding the outer circumferences of two superposed metal plates over the entire circumference. Thus, the present invention relates to a method and an apparatus for producing a hydrofoam molded article with high production efficiency by performing hydrofoam molding while ensuring sealing performance at the time of bulging deformation without sealing two metal plates.

  As is well known, press molding using a metal plate as a raw material is often used for a molded product of a thin plate used for automobiles, home appliances and the like. However, in press forming of metal plates, molding defects such as thinning and cracking are likely to occur at the deformation concentrated part formed by the corner R part of the mold, and the part formed by the punch bottom part is difficult to deform and can be formed. There is a problem that the degree of freedom of the shape is low, and the spring back after processing is inevitably generated, so that it is not easy to improve the dimensional accuracy of the molded product.

  On the other hand, in hydroforming, the pipe material that is the raw material or two superimposed metal plates are placed inside a pair of upper and lower molds, clamped, and pressurized working fluid is injected into the raw material. By doing so, the raw material is bulged and deformed so that the raw material is along the inner surface of the mold, and a molded product having an outer surface shape that matches the inner surface shape of the mold is manufactured. For this reason, in hydroforming, it is difficult to cause partial thinning or cracking in order to bulge and deform the entire material, and most parts are deformed in a biaxial tension state in order to utilize the bulging deformation. Therefore, the press molding has excellent features such that it is possible to mold a complicated shape that causes molding failure, and that the dimensional accuracy of the molded product can be increased because the spring back after processing is small. In recent years, hydroform molding has been proposed as a method for manufacturing various automotive parts in particular because it can improve productivity and reduce manufacturing costs by reducing the number of molds and processes.

  In hydroform molding, machining fluid is injected between two metal plates that are sandwiched between molds and pressed to form, so when the machining fluid leaks between the two metal plates, Since a high pressure cannot be generated, the metal plate cannot be bulged and deformed.

  For example, in Patent Document 1, two metal plates are welded on the outer periphery of a portion of the two metal plates that form the bulging deformation portion, and the gap between the two metal plates is sealed between the two metal plates. Disclosed is a method for producing a hydrofoam molded article by injecting a working fluid while preventing leakage of the working fluid.

  However, only a minute hole such as a pinhole exists in the welded portion of the two metal plates, and the machining fluid leaks from the hole, so that a high pressure of 50 MPa or more cannot be generated between the two metal plates. . For this reason, in order to carry out the method disclosed in Patent Document 1, it is necessary to weld two metal plates with extremely high reliability over the entire length of the welded portion, and it is easy to apply as a manufacturing method for mass-produced products. is not. Further, in the method disclosed in Patent Document 1, since the two metal plates are bulged and deformed in a state where the two metal plates are welded to each other, the degree of the bulging deformation of the two metal plates is not comparable. In this case, wrinkles are generated in the metal plate having a small degree of bulging deformation, that is, a metal plate arranged on the side of a mold having a hole type with a short line length, so that the shape that can be manufactured is considerably limited.

  In Patent Document 2, a bead is formed over the entire periphery of a hole mold provided in a mold, and the outer periphery of two metal plates stacked without being welded is pressed by this bead. A method of hydroforming while sealing two metal plates is disclosed.

  According to the invention disclosed in Patent Document 2, leakage of the machining fluid can be prevented to some extent by the bead provided in the mold, but according to the result of the study by the present inventor, the pressure that can be applied between the two metal plates Is at most about 30 to 50 MPa, and it is impossible to apply a high pressure of 50 MPa or more, particularly exceeding 100 MPa.

  Further, in Patent Document 3 and Non-Patent Document 1, the upper and lower molds are sealed with a seal ring, between the upper metal plate and the plate pressing surface of the upper mold, and between the lower metal plate and the lower mold. Sealing between the two metal plates by disposing a seal ring between each plate holding surface of the mold, and leakage of the processing liquid from between the two metal plates, between the upper mold and the lower mold, It is prevented between the upper mold and the upper metal plate, and further between the lower mold and the lower metal plate, and the two metal plates are bulged and formed by bulging and forming the high working fluid between the two metal plates. There is disclosed a method of hydroforming by applying a desired pressure between two metal plates without welding the two metal plates.

  In addition, in the normal seal ring disclosed by Non-Patent Document 1, it is difficult to seal a high-pressure machining fluid, and the pressure that can be applied between two metal plates is about 40 MPa. The pressure is increased by using a special seal ring that can seal high pressure.

JP-A-47-33864 Japanese Patent Laid-Open No. 2003-25022 JP 2008-119723 A

Hydroforming of Tube, Extrusions, and Sheets Vol3 (2003), p217-226

  The method disclosed in Patent Document 3 has the following problems because it seals between the upper mold and the lower mold and also seals between the upper and lower molds and the two metal plates.

(A) Reduction in yield Since it is necessary to dispose a seal ring on the plate holding surface of the mold, it is necessary to provide a flange portion larger than the product shape on the metal plate, resulting in a decrease in yield.

  Further, the special seal ring disclosed in Patent Document 3 has a complicated shape and a large cross-sectional shape. Further, although the metal plate is sealed by the seal ring, since the seal ring is an elastic body, a molding pressure is applied to the surface of the metal plate opposite to the seal ring, and a dent is generated in the metal plate. When this recessed portion formed by the outer peripheral side seal ring extends to the seal portion by the inner peripheral side seal ring, the inner peripheral side seal ring is not pressed down and seal leakage occurs. For this reason, it is necessary to secure a sufficient distance between the seal ring to the upper mold and the seal ring to the lower mold. From this point, it is necessary to provide a flange portion larger than the product shape on the metal plate. , The yield further decreases.

(B) Because of high-pressure sealing, mold processing accuracy, high mold rigidity, and blank thickness accuracy are required. When sealing with a seal ring, there is a gap between the seal ring groove and the blank. When a high pressure is applied, the seal ring protrudes from the gap. For this reason, when a blank is sandwiched between molds, there must be no gap. If the mold processing accuracy or the blank thickness accuracy is low, a gap is inevitably generated. Furthermore, when the rigidity of the mold is low, the mold is deformed by the molding pressure and a gap is generated. Therefore, it is necessary to manufacture a highly accurate and highly rigid mold, and to use a blank with strict tolerance, which increases costs.

(C) Seal leakage due to flange wrinkles When flange wrinkles occur due to the inflow of the metal plate, when the wrinkle portion reaches the seal ring, the seal ring cannot be pressed tightly and seal leakage occurs.

(D) Seal leakage due to changes in the plate thickness of the flange portion If the plate thickness changes partially to the flange portion due to uneven flange inflow, the seal ring cannot be pressed tightly and seal leakage occurs. Produce.

(E) Seal leakage will occur if the metal plate is thin. In the method using a seal ring, if the gap between the upper and lower molds is basically not the same as the thickness of the two metal plates, sealing will occur. Although the ring cannot be pressed, the plate thickness of the metal plate to be formed is not constant and varies depending on the specifications of the molded product. Therefore, when a thin metal plate is used, seal leakage occurs.

(F) It is difficult to manufacture a seal ring corresponding to a curved flange surface. A large ring with a complicated product shape is produced by turning a general lathe or by bonding both ends of a string-like seal ring material. If it fits into a seal ring groove according to the above, it cannot be applied because the cross-sectional shape changes due to bending deformation. Therefore, it is necessary to manufacture by three-dimensional cutting from the block, or manufacturing a dedicated mold and vulcanization molding. However, it is difficult to cut a seal ring material such as rubber, and vulcanization molding has deformation during heat treatment, so it is difficult to mold large-sized products with high accuracy.

  Furthermore, when the flange surface to which the seal ring is attached is a curved surface, the seal groove also has a three-dimensional shape. Not only is it very difficult to produce a seal ring according to the shape, but the accuracy required for high-pressure sealing cannot be obtained. .

(G) It is difficult to attach the seal ring to the upper mold. In order to place the seal ring on the upper mold, it is generally necessary to bond the seal ring to prevent it from falling off. Is a consumable and needs to be replaced, so it is not easy to replace it after bonding. In the first place, since the seal ring disclosed in Patent Document 3 is not used by bonding, it may not be applicable to hydroforming.

(H) Formability is reduced Since the metal plate receives the hydraulic pressure of the machining fluid inside the seal ring, the flange is difficult to flow in due to friction with the mold at the plate pressing portion, and the moldability is reduced. descend.

  The present invention has been made in view of these problems, and with a simple configuration, sufficiently secures sealing properties during bulging without having to weld the outer circumferences of two superimposed metal plates over the entire circumference. An object of the present invention is to provide a method and an apparatus for producing a hydrofoam molded product with high production efficiency by performing hydrofoam processing with a moldability superior to that of the prior art.

  In hydroforming, if a working fluid is injected between two steel plates that are overlapped with a pair of upper and lower molds sealed, one steel plate swells inside the hole mold provided in the upper mold. While deforming, the other steel plate bulges and deforms inside the hole mold provided in the lower mold. At this time, the contact surface pressure with the steel plate concentrates on the mold shoulder R portion formed in a curved surface continuously on the plate pressing surfaces of the upper and lower molds.

  As a result of examining the hydroforming molding process in detail, the inventor can maintain a state in which the contact surface pressure is higher than the molding pressure of the working fluid at all times of bulging deformation. The steel plates are sealed by the mold shoulder R at all times of bulging deformation, so that the working fluid does not leak from between the steel plates and the mold, and the two steel plates that are overlapped, for example, by welding Even without seal welding, a simple configuration ensures sufficient sealing performance during bulging deformation, while hydroforming is performed with better formability than before to produce hydroformed molded products with high production efficiency As a result, the present invention has been completed.

  The present invention includes a plate pressing surface that presses one of the two stacked metal plates in the plate thickness direction, and a mold shoulder R portion formed in a curved surface continuously from the plate pressing surface. A first metal mold that is partially formed and has a hole mold that has the same inner shape as the outer shape of a hydroform molded product by hydroforming, and the other metal of the two metal plates A part is formed by a plate pressing surface that presses the plate in the plate thickness direction, and a mold shoulder R portion formed in a curved shape continuously with the plate pressing surface, and a hydroforming molded product by hydroforming The first step of sandwiching the two metal plates by the plate pressing surfaces using a second mold having a hole mold having the same inner shape as the outer shape, and between the two metal plates For hydroforming By supplying a working fluid to the portion that forms the bulging deformation portion, both of the two metal plates are bulged and deformed, and one of the metal plates is aligned with the inner surface of the hole mold of the first mold. By placing the other metal plate along the inner surface of the hole mold of the second mold, a first hydroform product using one metal plate as a material and a second hydroform using the other metal plate as a material And a second step of manufacturing a molded article, wherein the two metal plates that are overlaid are not sealed, and the first mold and the second mold are respectively pressed against each other. In the second step, the contact surface pressure between the mold shoulder R portion of the first mold and one metal plate is at least expanded over the entire circumference of the mold shoulder R portion. At all times of deformation The mold shoulder R portion of the first mold is brought into contact with one metal plate so as to be higher than the pressure of the machining fluid supplied between the metal plates, and the mold shoulder R portion of the second mold is The contact surface pressure with the other metal plate is higher than the pressure of the working fluid supplied between the two metal plates over the entire circumference of the mold shoulder R and at least during the entire bulging deformation. A method for producing a hydroform molded article, characterized in that the mold shoulder R portion of the second mold is brought into contact with the other metal plate.

  In the manufacturing method according to the present invention, it is desirable that the radius of curvature of the mold shoulder R portion satisfy the relationship defined by the following formula (1): 1 <ρ / t <7.5 over the entire circumference. Here, ρ is the radius of curvature (mm) of the mold shoulder R portion, and t is the thickness (mm) of the metal plate in contact with the mold shoulder R portion.

  In these manufacturing methods according to the present invention, each of the pair of molds is a portion where there is no significant expansion or contraction in the direction perpendicular to the inflow direction during the inflow (more specifically, the expansion flange deformation and the contraction flange deformation are hardly caused. It is desirable to provide metal plate inflow resistance means disposed on the plate pressing surface of a portion that does not occur and is hereinafter referred to as a “portion where the metal plate easily flows”.

  The part where stretch flange deformation and contraction flange deformation hardly occur means a part where the outer peripheral part of the flange hardly undergoes plastic deformation during molding, in other words, the thickness of the outer peripheral edge of the flange is almost increased. It is a part that does not have any thickness, and specifically, a part where the thickness change rate (ratio of change in thickness after molding to thickness before molding) of the flange outer peripheral edge is 1% or less. It is.

  From another point of view, the present invention is formed in a curved surface continuously with the plate pressing surface for pressing one metal plate in the thickness direction of the two stacked metal plates, and the plate pressing surface. A first mold having a part formed by the mold shoulder R portion and having a hole mold having the same inner shape as the outer shape of the hydroformed product by hydroforming, and two metal plates A part is formed by a plate pressing surface for pressing the other metal plate in the plate thickness direction, and a mold shoulder R portion formed in a curved shape continuously to the plate pressing surface, and hydroform molding. And a second mold having a hole mold having the same outer shape as the outer shape of the hydroform molded product, and between the two metal plates sandwiched by the plate pressing surfaces and by hydroforming Bulge deformation By supplying the machining fluid to the part forming the two metal plates, both of the two metal plates are bulged and deformed so that one metal plate is placed along the inner surface of the hole mold of the first mold and the other metal plate is A first hydroform molded product made from one metal plate and a second hydrofoam molded product made from the other metal plate are manufactured by being along the inner surface of the hole mold of the second mold. An apparatus for manufacturing a hydroform molded product, wherein the first mold and the second mold are sealed on the outside of each plate pressing surface, and the mold shoulder R portion of the first mold is The contact surface pressure with one of the metal plates is higher than the pressure of the working fluid supplied between the two metal plates over the entire circumference of the mold shoulder R and at least all the time of the bulging deformation. Is a seal part that contacts one metal plate In both cases, the mold shoulder R portion of the second mold has two contact surface pressures with the other metal plate over the entire circumference of the mold shoulder R portion and at least at all times of bulging deformation. An apparatus for manufacturing a hydroform molded product, which is a seal portion that comes into contact with the other metal plate so as to be higher than the pressure of the working fluid supplied between the metal plates.

  In the manufacturing apparatus according to the present invention, the radius of curvature of the mold shoulder R portion of the first mold and the radius of curvature of the mold shoulder R portion of the second mold are both the above ( It is desirable to satisfy the relationship defined by equation (1).

According to the present invention, it is possible to bulge and form a metal plate by preventing leakage of the working fluid and applying a high pressure without sealing between the two metal plates stacked.
Further, according to the present invention, the first hydroform molded product having the same outer surface shape as the inner surface shape even when the inner surface shapes of the first hole mold and the second hole mold are greatly different. And since the 2nd hydrofoam molded product can be manufactured, the outstanding productivity and cost reduction can be aimed at.

  Furthermore, since a blank smaller than a conventional hydroformed molded product of a metal plate can be used, the yield can be improved and the molded product can be reduced in weight.

FIG. 1 is a perspective view showing a configuration of a manufacturing apparatus according to the present invention in a transparent state and partially simplified. 2 (a) to 2 (f) are central cross sections in the case where the working fluid is injected into the portion forming the bulging deformed portion between the two steel plates in the first step and the second step. It is explanatory drawing which shows typically the deformation | transformation behavior of these two steel plates. FIG. 3 is a graph showing the molding pressure at the time of molding, the surface pressure of the mold shoulder R portion, and the inflow amount of the flange end in the central section. FIG. 4 is a graph showing the surface pressure behavior when the radius of curvature ρ of the mold shoulder R is 3, 6, or 12 mm. FIG. 5 is a graph showing the relationship between the ratio of the radius of curvature ρ of the mold shoulder R portion to the thickness t of the steel plates 4 and 5 and the margin pressure when the forming pressure is reduced. FIG. 6 is an explanatory view showing a seal between a steel plate and a mold using a conventional seal ring, and FIG. 6 (a) shows a case where the gap between the plate pressing surfaces is equal to the plate thickness of the two steel plates. FIG. 6B shows a case where the gap between the plate pressing surfaces is different from the thickness of the two steel plates. FIG. 7 is an explanatory view showing a seal between a steel plate and a mold not using the seal ring of the present invention. FIG. 7 (a) shows a case where the gap between the plate pressing surfaces is equal to the plate thickness of the two steel plates. FIG. 7B shows a case where the gap between the plate pressing surfaces is different from the plate thickness of the two steel plates. FIG. 8A is a top view of the hole mold used in Example 1, FIG. 8B is a cross-sectional view of this hole mold, and FIG. 8C is a vertical cross-sectional view of this hole mold. . FIG. 9A is a top view of a hole mold used in Example 4, FIG. 9B is a cross-sectional view of this hole mold, and FIG. 9C is a vertical cross-sectional view of this hole mold. . FIG. 10 is an explanatory view showing the shapes of two steel plates used in Example 2, in which FIG. 10 (a) is an upper plate and FIG. 10 (b) is a lower plate. FIG. 11 is a cross-sectional view of two molded products obtained by forming a steel plate having a thickness of 980 MPa and a thickness of 1.2 mm according to Example 1, and is a longitudinal cross-sectional shape explanatory diagram illustrating a spring back in the longitudinal direction of the molded product. Fig.12 (a) is explanatory drawing which shows the die | dye of the crimping tool used in Example 5, FIG.12 (b) is sectional drawing which shows the crimping tool arrange | positioned at a metal mold | die.

  The present invention will be described in detail with reference to the accompanying drawings. In the following description, the case where the metal plate is a steel plate is taken as an example, but the present invention is similarly applied to a metal plate other than the steel plate.

1. Manufacturing apparatus for hydroformed product according to the present invention FIG. 1 is a perspective view showing a configuration of a manufacturing apparatus 1 according to the present invention in a transparent state and partially simplified.

The manufacturing apparatus 1 includes a pair of a first mold 2 and a second mold 3. The mold 2 is an upper mold, and the mold 3 is a lower mold.
The mold 2 has a plate pressing surface 2a and a hole mold 2b. The plate pressing surface 2a is a plate thickness direction of one steel plate 4 positioned above the two steel plates 4 and 5 that are stacked without being sealed around the portions 4a and 5a that form the bulging deformed portion. Hold down. The hole mold 2b has the same inner shape (inner surface) 2c as the outer shape of the first hydrofoam molded product by hydroforming. A part of the hole mold 2b is formed by a mold shoulder R portion 2d formed in a curved shape continuously to the plate pressing surface 2a.

  On the other hand, the mold 3 has a plate pressing surface 3a and a hole mold 3b. The plate pressing surface 3a presses the other steel plate 5 positioned below the stacked two steel plates 4, 5 in the plate thickness direction. The hole mold 3b has the same inner shape (inner surface) 3c as the outer shape of the second hydroformed product by hydroforming. A part of the hole mold 3b is formed by a mold shoulder R portion 3d formed in a curved shape continuously to the plate pressing surface 3a.

  The shape of the inner surface 2c of the hole mold 2b and the shape of the inner surface 3c of the hole mold 3b may be significantly different. For this reason, according to the manufacturing apparatus 1, the first hydroform molded product and the second hydrofoam molded product having substantially different outer surface shapes can be manufactured at the same time, or the first hydroform having the same outer surface shape. The molded product and the second hydrofoam molded product can be manufactured at the same time.

  The manufacturing apparatus 1 has a bulging deformed portion formed by hydroform molding between two steel plates 4 and 5 from a machining liquid supply device (not shown) connected to a machining liquid inlet 3e formed in the mold 3. By supplying a working fluid to the portions 4a and 5a to be formed, the two steel plates 4 and 5 are swelled and deformed, and the steel plate 4 is moved along the inner surface 2c of the mold 2 to thereby form a first hydroform molded product. And a second hydroformed product is manufactured by bringing the steel plate 5 along the inner surface 3 c of the mold 3.

  The molds 2 and 3 are sealed by sealing means 7 disposed outside the plate pressing surfaces 2a and 3a. The mold 2 and the mold 3 are inlays, and a seal ring 7 c is disposed in a seal ring groove 7 a provided on the vertical wall of the mold 3.

  The seal means 7 is not limited to this configuration, and a seal ring with a normal backup ring that seals flat surfaces may be used. If there is no problem such as sliding with the steel plates 4 and 5 and the seals are flat, sealing is easy even at high pressure.

  Spacers 8 are arranged according to the plate thickness of the steel plates 4 and 5, and the gaps between the plate pressing surfaces 2a and 3a of the upper and lower molds 2 and 3 are adjusted. In particular, when there is no change in the plate thickness, the spacers may be omitted and the mold dimensions may be set according to the plate thickness.

  Furthermore, the mold shoulder R portion 2d of the first mold 2 has a contact surface pressure with the steel plate 4 over the entire circumference of the mold shoulder R portion 2d and at least during all times of bulging deformation. 5 is a seal portion that comes into contact with the steel plate 4 so as to be higher than the pressure of the working fluid supplied between the two. Further, the mold shoulder R portion 3d of the second mold has the contact surface pressure with the steel plate 5 over the entire circumference of the mold shoulder R portion 3d and at least all the time of the bulging deformation, 5 is a seal portion that comes into contact with the steel plate 5 so as to be higher than the pressure of the working fluid supplied between the two.

  The radius of curvature ρ (mm) of the mold shoulder R portions 2d and 3d is expressed by the following equation (1): 0.1 <ρ / t <7.5 (where t (mm) is the mold shoulder. It is desirable to satisfy the relationship defined by the thickness (mm) of the steel plates 4 and 5 in contact with the R portions 2d and 3d. If ρ / t is 0.1 or less, a sharp edge may be formed, and the steel sheet may be sheared. If ρ / t is 7.5 or more, there is a risk of seal leakage. In order to prevent the occurrence of shock marks, ρ / t is preferably 1 or more, and more preferably 4 or less in order to ensure a sufficient surface pressure.

  The mold shoulder R portions 2d and 3d may have a single R cross section, or the radius of curvature may change continuously. The radius of curvature of the mold shoulder R portions 2d and 3d in the present invention means the radius of curvature having the largest curvature in the cross section of the mold shoulder R portions 2d and 3d. This is because the largest curvature part contributes most to the seal.

  As a result, the contact surface pressure between the mold shoulder R portion 2d and the steel plate 4 in the mold 2 is more than the pressure of the working fluid over the entire circumference of the mold shoulder R portion 2d and at least all the time of bulging deformation. The contact pressure between the mold shoulder R portion 3d and the steel plate 5 in the mold 3 is increased over the entire circumference of the mold shoulder R portion 3d and at least all the time of the bulging deformation. Get higher.

  In addition, it is desirable to provide air vent holes 2f and 3f in the hole mold 2b of the mold 2 and the hole mold 3b of the mold 3 as in the plate press molding. Air punching holes are provided at the bottom of the punch in plate press forming, and at the corner of the bottom of the hole mold that finally swells in hydroforming of a normal steel plate. In the manufacturing apparatus 1 according to the present invention, an overrun of the flange is provided. Therefore, the air vent hole 2f is provided in the vicinity of the mold shoulder R portion 2d, and the air vent hole 3f is provided in the vicinity of the mold shoulder R portion 3d. It is desirable. The air vent 3f is arranged in the same manner as the air vent 2f, but is omitted in FIG. 1 for easy reading of the drawing.

  The configuration of the manufacturing apparatus 1 according to the present invention other than the above may be the same as that of a known hydroform molded product manufacturing apparatus, and these are well-known and commonly used by those skilled in the art, and thus further description is omitted. .

  The manufacturing apparatus 1 according to the present invention is configured as described above. Next, the manufacturing method according to the present invention will be described.

2. In the present invention, as in the prior art, the method for producing a hydrofoam molded article according to the present invention,
First step: The two stacked steel plates 4 and 5 are sandwiched between the plate pressing surface 2 a of the mold 2 and the plate pressing surface 3 a of the mold 3.
Second step: By supplying the processing liquid from the processing liquid inlet 3e to the portions 4a and 5a between the two steel sheets 4 and 5 and forming the bulging deformation portion, the two steel sheets 4 and 5 are A hydroform molded product is manufactured by causing the steel plate 4 to swell along the inner surface 2c of the mold 2 and the steel plate 5 along the inner surface 3c of the mold 3 by bulging and deforming.

  In the present invention, unlike the method disclosed in Patent Document 1, the two steel plates 4 and 5 that are overlapped do not need to be sealed between the steel plates 4 and 5, so that the portion that forms the bulging deformation portion Do not weld around 4a and 5a.

In the present invention, in the second step,
(A) Processing the mold shoulder R portion 2d so that the contact surface pressure between the mold shoulder R portion 2d and the steel plate 4 is over the entire circumference of the mold shoulder R portion 2d and at least all the time of bulging deformation. (B) The mold shoulder R portion 3d is brought into contact with the steel plate 4 so that the pressure is higher than the liquid pressure. The contact surface pressure between the mold shoulder R portion 3d and the steel plate 5 is the mold shoulder R portion 3d. The steel plates 4 and 5 are sealed by bringing them into contact with the steel plates 5 so as to be higher than the pressure of the working fluid over the entire circumference of the steel plate and at least in all the time of the bulging deformation. That is, the mold shoulder R portions 2 d and 3 d are both used as the seal portions of the steel plates 4 and 5.

The first step and the second step will be described over time.
2 (a) to 2 (f) show the case where the working fluid is injected into the portions 4a and 5a that form the bulging deformed portions between the steel plates 4 and 5 in the first step and the second step. It is explanatory drawing which shows typically the deformation | transformation behavior of the steel plates 4 and 5 in a center cross section. FIG. 3 is a graph showing the molding pressure at that time, the surface pressure of the mold shoulder R, and the inflow amount of the flange end in the central section. The working fluid injection volume ratio on the horizontal axis is the ratio of the working fluid injection volume to the product shape, and 100% is the shape along the hole shape. When the amount of inflow at the flange end increases with time, it means that the flange is moving in the hole shape direction, and when it decreases, it means that the flange is moving in the opposite direction. In addition, the graphs of FIGS. 3 to 5 are results obtained under the conditions where the steel plates 4 and 5 have a thickness of 1.6 mm and a strength level of 270 MPa.

[First step]
FIG. 2A shows a state in which two steel plates 4 and 5 are overlapped and set between the mold 2 and the mold 3. At this time, it is not necessary to press and hold the steel plates 4 and 5 between the plate pressing surface 2a of the mold 2 and the plate pressing surface 3a of the mold 3, but between the plate pressing surface 2a and the steel plate 4, or the plate pressing surface 3a. A gap is allowed between the steel plate 5 and the steel plate 5.

[Second step]
FIG. 2B shows a state in which the machining liquid has started to be injected between the steel plates 4 and 5, and shows a point I in the graph of FIG.

  The steel plate 4 sticks to the mold 2 and the steel plate 5 sticks to the die 3. The steel plate 4 bulges and deforms in the hole mold portion 2b, and the steel plate 5 bulges and deforms in the hole mold portion 3b. Since the molding pressure is extremely small, the contact surface pressure between the mold shoulder R portion 2d and the steel plate 4 and the contact surface pressure between the mold shoulder R portion 3d and the steel plate 5 are both sufficiently larger than the molding pressure. There is no risk of leakage.

FIG. 2C shows a point II in the graph of FIG. 3 in a state where the deformation has further progressed.
The bulging and deforming steel plate 4 is in contact with the inner surface (bottom portion) 2c-1 of the mold 2, and the bulging and deforming steel plate 5 is in contact with the inner surface (bottom portion) 3c-1 of the mold 3.

FIG. 2D shows a point III in the graph of FIG. 3 in a state where the deformation has further progressed.
The inner surface (vertical wall) 2c-2 of the mold 2 and the steel plate 4 are in contact with each other, and the inner surface (vertical wall) 3c-2 of the mold 3 and the steel plate 5 are in contact with each other. At this time, it does not contact the inner surface (vertical wall) 2c-2 along the mold shoulder R portion 2d, and does not contact the inner surface (vertical wall) 3c-2 along the mold shoulder R portion 3d. (Vertical wall) Abuts in the middle of 2c-2 and 3c-2. This is because the deformation of the mold shoulder R portions 2d and 3d cannot be deformed so much as the pressure of the molding liquid.

FIG. 2E shows a point IV in the graph of FIG. 3 in a state where the deformation has further progressed.
The mold 2 bulges so as to fill the unfilled portion of the inner surface (bottom portion) 2c-1 of the mold 2 and the unfilled portion of the inner surface (bottom portion) 3c-1 of the mold 3, but at this time, the mold shoulder R portion In the vicinity of 2d, the steel plate 4 overruns inside the hole mold 2b to generate an overrun portion 4b, and in the vicinity of the mold shoulder R portion 3d, the steel plate 5 overruns inside the hole mold 3b. An overrun portion 5b is generated. This is because the deformation of the mold shoulder R portions 2d and 3d cannot be deformed so much as the pressure of the molding liquid.

  FIG. 2 (f) shows a point V in the graph of FIG. 3, and after the inner surfaces (bottom portions) 2c-1 and 3c-1 of the molds 2 and 3 are filled, the pressure of the working fluid further increases. The overrun portions 4b and 5b are pushed back by hydraulic pressure and formed into a desired shape.

As described above, the flange inflow flows backward from FIG. 2E to FIG. 2F, and the maximum value of the surface pressure of the mold shoulder R portions 2d and 3d is greatly reduced.
When the maximum surface pressure of the mold shoulder R portions 2d and 3d decreases, if the pressure of the machining liquid falls, the machining liquid leaks to the hole molds 2b and 3b, and thereafter the pressure does not increase and molding failure occurs. It becomes.

  That is, if the shapes of the molds 2b and 3b of the molds 2 and 3 are close to the bulging shape, the molds 2 and 3 can be molded simply by sealing the molds 2 and 3; Molding is possible if the surface pressure of the mold shoulder R portions 2d and 3d is higher than the pressure of the working fluid over the entire circumference of 2b and 3b and at least at all times of bulging deformation.

  As described above, during the molding, the flange portion overruns into the hole molds 2b and 3b to generate overrun portions 4b and 5b, and then the overrun portions 4b and 5b run backward. This is the cause of the decrease in the surface pressure of the parts 2d and 3d, but the overrun of the flange part is that the steel plate 4 is not formed along the shape of the mold shoulder R portion 2d and the steel plate 5 is in the shape of the mold shoulder R portion 2d. Due to not being molded along.

  This is because the steel plate 4 bulges and deforms in the hole mold 2b and the steel plate 5 bulges and deforms in the hole mold 3b, but the processing liquid is applied to the front and back of the steel plates 4 and 5 outside the mold shoulder R portions 2d and 3d. This is because no pressure is applied to the molds 2 and 3 and no frictional force is generated, and the pressure flows without resistance. Therefore, the phenomenon as described above does not occur at the portion where the inflow resistance occurs when the flanges of the steel plates 4 and 5 such as the contraction flange and the stretch flange are inflow, and the steel plate 4 bulges along the mold shoulder R portion 2d. While being deformed, the steel sheet 5 bulges and deforms along the mold shoulder R portion 3d, does not overrun, and does not cause a decrease in surface pressure.

  That is, seal leakage during forming can occur at a portion where the inflow resistance of the flange is small and the steel plates 4 and 5 easily flow in, that is, a portion where no significant expansion or contraction occurs in the inflow orthogonal direction during the inflow.

Here, there are two methods for preventing a decrease in surface pressure.
The first method is a method in which the surface pressure of the mold shoulder R portions 2d and 3d is kept high so that the pressure is sufficiently high even if the pressure is reduced, and the second method is through molding. By preventing the overrun by causing the steel sheet 4 to bulge along the mold shoulder R portion 2d and to bulge the steel plate 5 along the mold shoulder R portion 3d, the surface pressure does not decrease. is there.

As a factor for achieving the first method, attention was paid to the curvature radii of the mold shoulder R portions 2d and 3d.
FIG. 4 is a graph showing the surface pressure behavior when the curvature radii ρ of the mold shoulder R portions 2d and 3d are 3, 6, and 12 mm.

  As shown in the graph of FIG. 4, when the radius of curvature ρ of the mold shoulder R portions 2d and 3d is 3 mm, the surface pressure is locally concentrated from the start of molding, and a high surface pressure can be secured. Even if the pressure decreases, a pressure sufficiently higher than the molding pressure can be maintained.

  On the other hand, when the radius of curvature ρ of the mold shoulder R portions 2d and 3d is 12 mm, the contact area becomes large and the surface pressure is low from the beginning. It becomes easy to leak seal leakage.

  5 shows the ratio of the curvature radius ρ of the mold shoulder R portions 2d and 3d to the thickness t of the steel plates 4 and 5 and the margin pressure Δp when the molding pressure is reduced (the molding pressure and the mold shoulder R portion shown in FIG. 3). It is a graph which shows the relationship with the difference of the maximum surface pressure.

As shown in the graph of FIG. 5, the marginal pressure increases rapidly from the ratio (ρ / t) of 7.5 or less, and seal leakage is difficult. When the ratio (ρ / t) is 4.0 or less, the value is about 20 MPa.
Next, the second method will be described.

As a method of increasing the flange inflow resistance, that is, a method of providing the metal plate inflow resistance means 9 on the plate pressing surface of the portion 10 where the steel plates 4 and 5 easily flow,
(A) A method of reducing the clearance between the upper and lower molds 2 and 3 and locally pressing the steel plates 4 and 5 at the site 10 where the inflow resistance is to be increased. (B) A method of increasing the inflow resistance by arranging draw beads. ) Method of increasing the friction coefficient between the mold 2 and the steel plate 4 on the plate pressing surface 2a and the friction coefficient between the mold 3 and the steel plate 5 on the plate pressing surface 3a (d) There are methods such as inflow resistance.

  The increase in inflow resistance here does not need to be so large as to contribute to plastic deformation of the steel plates 4 and 5 as in the case of draw beads in press forming, and is slightly increased along the mold shoulder R portions 2d and 3d. Any material can be used as long as it becomes a resistance. In this case, the mold shoulder R portions 2d and 3d are preferably larger in order to make it easier to follow the steel plate 4 along the mold shoulder R portion 2d and to easily follow the steel plate 5 along the mold shoulder R portion 3d. This is because if the overrun does not occur, the pressure drop does not occur.

3. The reason why the formability is improved by the present invention The reason why the formability of the steel plates 4, 5 is improved by the present invention will be described.

  Since the hydroforming of the steel plates 4 and 5 is bulge forming, the entire steel plates 4 and 5 are plastically deformed, and the deformation is not concentrated on the mold shoulder R portions 2d and 3d. It is. However, thinning is likely to occur at portions that deform so as to fill the space at the end of the bulge, such as the corners of the hole molds 2b and 3b.

Therefore, in such a part, it is desirable that the flange easily flows in, the steel plate 4 is easily supplied into the hole mold 2b, and the steel plate 5 is easily supplied into the hole mold 3b. In hydroform molding using two steel plates that are circumferentially welded, the pressure of the working fluid is received up to the inside of the weld line, so friction occurs between the mold and the steel plate, making it difficult for the flange to flow in. Since the hydroforming method described in Document 3 also receives the pressure of the working fluid up to the inside of the seal ring, there is a problem that friction occurs between the mold and the steel plate, and the flange is difficult to flow in.

  On the other hand, in the manufacturing method according to the present invention, the flange portion, which is outside the mold shoulder R portions 2d and 3d, receives the hydraulic pressure from both surfaces of the steel plates 4 and 5, and therefore the force that presses the steel plate 4 against the mold 2 , And no force to press the steel plate 5 against the mold 3, no friction resistance between the mold 2 and the steel plate 4, and no friction resistance between the mold 3 and the steel plate 5, It becomes very easy to flow in. Therefore, the moldability at the corners of the hole mold, which is difficult with the conventional hydroform molding, is improved.

4). Reasons for improving the yield and reducing the weight of the product by the present invention In the hydroform forming of a steel plate in which the entire circumference of two steel plates is welded, lap welding such as laser welding or seam welding is performed in order to ensure the welding strength. It is necessary to carry out, and the welding allowance for that amount is required. Therefore, it is necessary to secure a certain flange width after molding. In order to make use of welding, the molded product has the final molded shape, but the outer peripheral shape varies, so the weld line after molding cannot be set at the edge of the hole mold edge. In addition, since it is necessary to set a welding line, it is necessary to set a wide flange width. Accordingly, an increase in product weight is inevitable.

  In the method disclosed in Patent Document 3, as described above, the flange width is determined in consideration of the seal ring. Therefore, it is necessary to provide a flange with a size larger than necessary as a product, and the yield is reduced by trimming after molding. To do.

  On the other hand, according to the manufacturing method of the present invention, since the flange portion basically does not contribute to the molding, it is possible to set the outer peripheral position after molding to a position close to the edge of the hole molds 2b and 3b. is there. The width of the flange can be selected as required. Therefore, the blank shape can be reduced, the yield can be improved, and the flange shape can be determined according to the performance of the product, so that the product can be reduced in weight.

5. The reason why the present invention is superior in sealing performance to the use of a seal ring At first glance, as shown in Patent Document 3, it is better to provide a seal ring between the steel plates 4 and 5 and the molds 2 and 3. It tends to be considered that the sealing performance between the molds 2 and 3 is improved. However, the reason why the sealing performance is deteriorated by using the seal ring will be described with reference to FIGS.

  6 is a cross-sectional view of the molds 12 and 13 of the sealing method using the seal ring 11 according to Patent Document 3, and FIG. 7 is a cross-sectional view of the molds 16 and 17 of the seal method of the present invention. FIG.

  6 (a) and 7 (a) show the case where the gap C0 between the upper and lower molds 12, 13 is equal to the thickness of the two steel plates 14, 15, and between the upper mold 12 and the upper steel plate 14, The gaps between the upper steel plate 14 and the lower steel plate 15 and between the lower steel plate 15 and the lower mold 13 are all zero. As long as this gap can be maintained during molding, seal leakage does not occur by either method. However, when the variation of the plate thickness of the steel plates 14 and 15, the change of the plate thickness due to the flange inflow, or the change of the gap between the dies 12 and 13 due to the elastic deformation of the dies 12 and 13, the seal ring is reversed. Deteriorates sealing performance. The reason will be described by taking as an example the case where the steel plate is thick.

6 (b) and 7 (b) are diagrams showing the case where the thick steel plates 14 and 15 are used in FIGS. 6 (a) and 7 (a).
If the gap between the molds on the inclined surface of the plate pressing surface is C1, which is the thickness of the thickness of the two steel plates, the gap C2 between the molds at other locations is larger than C1. In that case, as shown in FIG. 6B, the method of Patent Document 3 cannot press and crush the seal ring. Since the seal ring secures sealing performance by crushing a predetermined crushing margin, seal leakage occurs. Next, it is the surface pressure of the mold shoulder R portion. If there is no seal ring, a high surface pressure can be ensured because the load due to the pressure applied in the hole mold is handled only by the mold shoulder R portion. If there is a seal ring near the mold shoulder R portion, the seal ring is also responsible for the load, so that the surface pressure of the mold shoulder R portion becomes insufficient and seal leakage occurs.

  In other words, the sealing performance is deteriorated due to the arrangement of the seal ring near the mold shoulder R portion, and in order to eliminate the influence of the arrangement of the seal ring, the seal ring is separated from the mold shoulder R portion. If the seal ring is disposed at a different position, the yield and the moldability are lowered as described above.

  On the other hand, according to the present invention shown in FIGS. 7 (a) and 7 (b), the load due to the pressure applied in the hole mold is applied only to the mold shoulder R portions 16a and 17a without using the seal ring. Bulges without being affected by variations in the thickness of the steel plates 14 and 15, changes in the thickness due to flange inflow, and changes in the gap between the dies 12 and 13 due to elastic deformation of the dies 12 and 13. A high surface pressure can be maintained during deformation. Naturally, since the gap C2 between the molds is larger than C1 which is the thickness of the two steel plates, there is a gap between the steel plate 14 and the steel plate 15; Since the surface pressure is concentrated in the portion and a high surface pressure is maintained thereafter, as shown in Example 1 described later, seal leakage does not occur in a gap of about 30% of the plate thickness.

  A molding test was performed by applying the mold 11 having the shape shown in FIG. 8 to the manufacturing apparatus 1 shown in FIG. 8A is a top view of the hole mold 12, FIG. 8B is a cross-sectional view of the hole mold 12, and FIG. 8C is a vertical cross-sectional view of the hole mold 12. A solid line in FIG. 8A indicates the shape of the hole mold 12, and a two-dot chain line indicates the shape of the steel plate.

  The dimensions of the mold 11 are L1 = 300 mm, W1 = 100 mm, H1 = 30 mm, H2 = 10 mm, θ1 = θ2 = 45 degrees, Ra1 = Ra2 = 6 mm, Rb1 = Rb2 = 10 mm. The dimensions of the steel plate are Lb = 410 mm, WB = 170 mm, Lo = 215 mm.

  The forming test was conducted with the steel plate made of 270-980 MPa class and the steel plate thickness of 1.0-2.3 mm. The gap between the upper and lower molds was {(steel plate thickness) × 2 + α}, and the test was performed with a clearance α = 0.05 mm or less or 0.1 mm.

  The results are summarized in Table 1. A circle in Table 1 means that the gap between the molds is {(steel plate thickness) × 2 + 0.1} mm and there is no seal leakage up to a molding pressure of 150 MPa, and a triangle indicates that the gap between the molds is {(of the steel sheet). It means that the seal leaks to a molding pressure of 90 MPa at a plate thickness) × 2 + 0.1} mm, but there is no seal leak up to a molding pressure of 150 MPa when the gap between the molds is {(plate thickness of the steel plate) × 2 + 0.05} mm.

  With a thin, high-strength material (plate thickness: 1.0 mm, strength level: 980 MPa), when the clearance is 0.1 mm, wrinkles generated by the shrinkage flange reach the mold shoulder R portion, and seal leakage occurs. By setting the thickness to 05 mm or less, molding was possible without causing seal leakage under all conditions. In addition, the maximum thickness reduction was 30% or less, satisfying the requirements as a product.

  Furthermore, using a steel plate with a thickness of 1.6 mm of 590 MPa class, the radius of curvature of the mold shoulder R (Ra1, Ra2) was changed to 3, 6.9, 12, and 15 mm, and the test was performed with a clearance of 0.1 mm. However, when the radius of curvature of the mold shoulder R portion was 9 mm or less, the mold could be molded without leaking the seal once in 1000 tests. When the curvature radius of the shoulder portion of the mold was 12 mm and 15 mm, seal leakage occurred three times in 1000 tests.

  Further, a steel plate having a thickness of 1.6 mm of 590 MPa class was used, and the sealing property was investigated by changing the clearance. Even when the clearance was 0.4 mm, seal leakage did not occur at 100 MPa or more. Seal leakage occurred when the clearance was 0.5 mm, but the molding pressure could be secured up to 90 MP.

  As a comparison, when a 270 MPa class steel plate with a thickness of 1.2 mm was used to form a welded sheet, wrinkles were generated in the lower plate, and the desired shape (hole shape) could be formed. There wasn't.

  Furthermore, a steel plate having a thickness of 1.6 mm of 270 MPa class is formed by using a mold having a seal ring groove at a position 15 mm from the R stop of the upper mold and 30 mm from the R stop of the lower mold. When the blank dimensions Lb = 440 and WB = 230 were formed in accordance with the dimensions of the seal ring used, the reduction ratio was 30% at the mold bulge corner, making it unsuitable as a product. Furthermore, since the blank shape became larger, the product yield decreased by 45%.

  Under the same conditions as in Example 1, a forming test was performed using irregularly shaped steel plates 13 and 14 (780 MPa class, plate thickness 1.6 mm) shown in FIG. FIG. 10A shows an upper plate, and FIG. 10B shows a lower plate.

Since the amount of inflow differs between the upper and lower plates 13 and 14, the width of the lower plate 14 is set smaller than that of the upper plate 13. The width Wu of the upper plate 13 is 153 mm, and the width Wl of the lower plate 14 is 136 mm.
When the steel plates 13 and 14 were formed, the long side portion after forming was uniformly formed at a position 10 mm from the R stop of the mold shoulder R portion.

  Similarly to Example 1, a molding test was performed by applying the mold 11 shown in FIG. 8 in which the length of the hole mold 12 was increased to the manufacturing apparatus 1 shown in FIG. In this molding test, the length of the hole mold 12 is increased so that the center portion of the flange portion is almost free from expansion and contraction. The test was performed under the condition that the surface pressure concentration at the shoulder R hardly occurs. The shape of the hole mold 12 was L1 = 900 mm, the radius of curvature of the mold shoulder R portion was 15 mm, the shape of the steel sheet was Lb = 1010, and other dimensions were the same as those of the mold of Example 1.

When a test was conducted using a steel plate having a clearance of 0.1 mm, a thickness of 1.6 mm and a 590 MP class, seal leakage occurred.
Therefore, when a draw bead having a width of 5 mm and a depth of 1 mm was arranged at a position 20 mm from the R stop of the straight piece portion, it could be formed into a desired shape with 100 MP without leaking a seal.

  A molding test was performed by applying the mold 15 having the shape shown in FIG. 9 to the manufacturing apparatus 1 shown in FIG. 9A is a top view of the hole mold 16, FIG. 9B is a transverse sectional view of the hole mold 16, and FIG. 9C is a longitudinal sectional view of the hole mold 16.

  The dimensions of the mold 15 are L2 = 200 mm, W2 = 70 mm, θ3 = 15 °, Rc = 100 mm, H4 = 30 mm, H5 = 30 mm, θ4 = θ5 = 85 degrees, Ra4 = Ra5 = 6 mm, Rb4 = Rb5 = 10 mm Yes, the gap δ2 between the plate pressing surfaces is 3.25 mm, and the water injection holes and the like are the same as in FIG.

The dimension of the steel plate is 540 × 170 mm. The plate thickness of the steel plate was made into two types, 1.6 mm and 1.55 mm.
A test was performed using a 270 to 980 MPa grade steel plate, and all of them could be molded without sealing leakage at a molding pressure of 100 MPa.

  As a comparison, a seal ring was provided by providing a seal ring groove on the outer periphery of the upper mold 10 mm from the mold shoulder R portion and 35 mm from the lower mold shoulder R portion. Since the seal ring has a complicated three-dimensional shape, the cross section cannot be reduced in size, and the cross section is about 10 mm square. Machining is also difficult and requires excessive costs. Since it fell only by being inserted in the upper mold, it was bonded with an adhesive.

  The steel plates with a plate thickness of 1.6 mm could be formed except for 980 MPa, but all the steel plates with a plate thickness of 1.55 m caused seal leakage at 90 MPa or less. When the seal leaked, the seal ring was broken and an attempt was made to replace it. However, it was extremely difficult to replace because the whole was bonded.

  FIG. 11 is a cross-sectional view of molded products 17 and 18 in which a steel plate having a thickness of 980 MPa and a thickness of 1.2 mm is formed according to Example 1, and is a longitudinal cross-sectional shape explanatory diagram illustrating the spring back in the longitudinal direction of the molded product 18. is there.

  As shown in the figure, at the time of removal from the mold 11, the molded product 18 made of the lower plate with a small overhang is deformed by the spring back, and then joined by spot welding together with the molded product 17 made of the upper plate. It was difficult to do.

  Therefore, after caulking tools 19 are arranged at eight positions 11a indicated by circles in the mold 11 in FIG. 8A to complete the molding and reduce the molding pressure, the caulking tool 19 composed of a punch and a die is used. The molded products 17 and 18 were caulked and joined using

FIG. 12A is an explanatory view showing the die 21 of the caulking tool 19, and FIG. 12B is a cross-sectional view showing the caulking tool 19 arranged in the mold 11.
As shown in FIGS. 12A and 12B, the caulking tool 19 includes a punch 20 and a die 21, and the punch 20 is embedded in the upper die, and the die 21 is embedded in the lower die. . Since the molding pressure is also applied to the punch 20 and the die 21 during hydroforming, a seal ring 22 is disposed on each of the punch 20 and the die to prevent water leakage to the outside of the mold.

  Molding water accumulates in the recess 21a of the die 21 during handling of the raw material or the molded product, or the molding water does not accumulate (there is no molding water). When forming the steel sheet which is the material of the molded products 17 and 18 by hydraulic pressure, if the concave portion 21a is not filled with forming water but air is in the state, the surface 18a opposite to the surface in contact with the die 21 of the steel plate. When a hydraulic pressure is applied to the steel plate, the steel plate is pushed into the recess 21a, and the steel plate is wrinkled. Further, when the punch 20 is advanced in a state where the forming water is filled in the recess 21a, the steel sheet may not be deformed into a predetermined shape by the pressure of the forming water, and the caulking and bonding may not be performed.

  Therefore, a drain hole 23 is provided in the die 21. The drain hole 23 communicates with the hole 21a from the outer peripheral groove 24a of the top 24 press-fitted from the bottom of the die 21 to the side surface, and communicates with the mold surface through the gap 21b on the outer periphery of the die 21. It is comprised so that it may be guide | induced to the outer side of a steel plate through the thin groove | channel 21c carved.

  After the molding is completed and the molding pressure is reduced, the molded products 17 and 18 taken out after caulking by the caulking tool 19 composed of the punch 20 and the die 21 are caulked and joined. Also, there was no spring back, and it had the same shape as the hole shape.

  As shown in the fifth embodiment, due to the spring back, the molded product 18 made of the lower plate is deformed in a direction in which both end portions 18a in the longitudinal direction are separated from the molded product 17 made of the upper plate. On the other hand, the longitudinal end portions 18a of the molded product 18 made of the lower plate and the both longitudinal end portions 17a of the molded product 17 made of the upper plate have substantially the same amount of flange inflow, and the amount thereof is also small. . Therefore, two steel plates with a thickness of 980 MPa 1.2 mm are used as the upper plate and the lower plate, and the respective steel plates are overlapped and the short sides are joined discontinuously by spot welding at a pitch of 20 mm as a forming material. A molding test was conducted using the same.

  As a result, also in this forming test, the upper plate and the lower plate flowed in and the spot welding could be formed without breaking, as in the case where the two steel plates were not welded as the forming material. The two plates were joined by spot welding, and although there was a slight gap in the unjoined flange portion, joining by spot welding could be performed at any location without difficulty in the next process.

DESCRIPTION OF SYMBOLS 1 Manufacturing apparatus 2 according to the present invention Mold 2a Plate holding surface 2b Hole mold 2c Inner surface 2c-1 Inner surface (bottom)
2c-2 Inner surface (vertical wall)
2d Mold shoulder R portion 2e Processing fluid injection port 2f Air vent hole 3 Mold 3a Plate pressing surface 3b Hole mold 3c Inner surface 3c-1 Inner surface (bottom)
3c-2 Inner surface (vertical wall)
3d Mold shoulder R portion 3e Processing fluid injection port 3f Air vent holes 4, 5 Steel plates 4a, 5a Parts 4b, 5b forming bulging deformed portions 7 Seal rings 8 Spacers 9 Metal plate inflow resistance means 10 Parts 11 that easily flow in Die 11a Caulking tool placement position 12 Hole molds 13 and 14 Steel plate 15 Die 16 Hole molds 17 and 18 Molded product 18a Opposite surface 19 Caulking tool 20 Punch 21 Die 21a Recess (hole)
21b Clearance 21c Narrow groove 22 Seal ring 23 Drain hole 24 Top 24a Peripheral groove

Claims (5)

A part is formed by a plate pressing surface for pressing one of the two metal plates stacked in the thickness direction, and a mold shoulder R portion formed in a curved shape continuously to the plate pressing surface. And a first metal mold having a hole mold having the same inner shape as the outer shape of the hydroformed product formed by hydroforming, and the other metal plate of the two metal plates. A part of the plate pressing surface pressed in the plate thickness direction and a mold shoulder R portion formed in a curved shape continuously with the plate pressing surface, and the outer shape of the hydroformed product by hydroforming, Using a second mold having a hole mold having the same inner shape, a first step of sandwiching the two metal plates by the plate pressing surfaces, and between the two metal plates The hydroform By supplying a working fluid to a portion that forms a bulging deformation portion by shape, both of the two metal plates are bulged and deformed, and the one metal plate is transformed into the inner surface of the hole mold of the first mold. And the other metal plate along the inner surface of the hole mold of the second mold, whereby the first hydroform molded product made of the one metal plate and the other metal plate are In the manufacturing method of a hydrofoam molded article provided with the 2nd process of manufacturing the 2nd hydrofoam molded article made into a raw material,
Between the two stacked metal plates is not sealed, and the first mold and the second mold are sealed outside the respective plate pressing surfaces, and in the second step,
The contact surface pressure between the mold shoulder R portion of the first mold and the one metal plate is around the entire circumference of the mold shoulder R portion and at least at all times of bulging deformation. The mold shoulder R portion of the first mold is brought into contact with the one metal plate so as to be higher than the pressure of the machining fluid supplied between the metal plates,
The contact surface pressure between the mold shoulder R portion of the second mold and the other metal plate is over the entire circumference of the mold shoulder R portion, and at least at all times of bulging deformation. A hydroform molded product characterized in that the mold shoulder R portion of the second mold is brought into contact with the other metal plate so as to be higher than the pressure of the machining fluid supplied between the metal plates. Production method. The method for manufacturing a hydroformed molded product according to claim 1, wherein the radius of curvature of the mold shoulder R portion satisfies the relationship defined by the following formula (1) over the entire circumference.
0.1 <ρ / t <7.5 (1)
Here, ρ is the radius of curvature (mm) of the mold shoulder R portion, and t is the thickness (mm) of the metal plate in contact with the mold shoulder R portion.   The said pair of metal mold | die each manufactures the hydroform molded article described in Claim 1 or Claim 2 provided with the metal plate inflow resistance means arrange | positioned at the board pressing surface of the site | part into which the said metal plate flows easily. Method. A part is formed by a plate pressing surface for pressing one of the two metal plates stacked in the thickness direction, and a mold shoulder R portion formed in a curved shape continuously to the plate pressing surface. And a first metal mold having a hole mold having the same inner shape as the outer shape of the hydroformed product formed by hydroforming, and the other metal plate of the two metal plates. A part of the plate pressing surface pressed in the plate thickness direction and a mold shoulder R portion formed in a curved shape continuously with the plate pressing surface, and the outer shape of the hydroformed product by hydroforming, A second mold including a hole mold having the same inner shape, and forming a bulging deformed portion by the hydroform molding between the two metal plates sandwiched between the plate pressing surfaces. To do By supplying a machining fluid to the two metal plates, both of the two metal plates are bulged and deformed so that the one metal plate is aligned with the inner surface of the hole mold of the first mold and the other metal plate is A first hydroform molded product using the one metal plate as a material and a second hydroform molded product using the other metal plate as a material by being along the inner surface of the hole mold of the second mold. Hydroform molded product manufacturing equipment for manufacturing
The first mold and the second mold are sealed on the outside of the plate pressing surface, and the mold shoulder R portion of the first mold is formed with the one metal plate. The contact surface pressure is higher than the pressure of the machining fluid supplied between the two metal plates over the entire circumference of the mold shoulder R and at least during all the bulging deformation. And a seal part that contacts the metal plate of
The mold shoulder R portion of the second mold has the contact surface pressure with the other metal plate over the entire circumference of the mold shoulder R portion and at least at all times of bulging deformation. An apparatus for manufacturing a hydroform molded product, which is a seal portion that comes into contact with the other metal plate so as to be higher than the pressure of the processing liquid supplied between the metal plates. The radius of curvature of the mold shoulder R portion of the first mold and the radius of curvature of the mold shoulder R portion of the second mold are both defined by the following formula (1) over the entire circumference. The apparatus for producing a hydroformed molded product according to claim 4 satisfying the above relationship.
1 <ρ / t <7.5 (1)
Here, ρ is the radius of curvature (mm) of the mold shoulder R portion, and t is the thickness (mm) of the metal plate in contact with the mold shoulder R portion.

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